A Plasma-Electrolyte Method of Obtaining Thin-Walled Hollow Particles of Silicon Oxide

A single-stage plasma-electrolyte method for the synthesis of hollow particles of silicon dioxide (SiO2) from an aqueous solution of liquid glass without the use of solid templates. A contact glow discharge in the electrolyte was maintained by a dc source with smooth regulation of the output voltage in the range of 0–400 V and a current of 0–10 A in an alkaline solution of Na2SiO3 (≈5 g/L SiO2, pH ≈ 12). The morphology of the obtained particles was studied using scanning electron microscopy (SEM). It was found that the main product is hollow spherical particles with a diameter of 0.5–2 µm (D50 ≈ 1.1 µm). Based on SEM images of the destroyed spheres, the shell thickness was estimated to be about 50–120 nm, which corresponds to a relative thickness of t/D ≈ 0.05–0.10. The mechanism of formation of hollow spheres and possible areas of application of the obtained microspheres as lightweight fillers and platforms for subsequent functionalization are discussed.